Chattanooga surgeon pioneers minimally invasive alternative to total knee replacement

Total knee replacement is a big, brutal operation with a long recovery. It is usually effective at eliminating debilitating knee pain from end stage arthritis, but it comes with some risks and a long arduous rehabilitation. Some studies have shown up to a 20 % rate of dissatisfaction after surgery. In one local orthopedic surgeon's opinion, at least half of these surgeries are not needed, instead a much safer technique that spares muscle and ligaments and utilizes a short incision and a small fraction of the amount of metal and plastic. This procedure, minimally invasive partial knee resurfacing using the Repicci technique, has been a special interest of Dr. Marty Redish for nearly 20 years.

"At least half of the patients who undergo total knee replacement today do not need the surgery in my opinion," explained Dr. Martin Redish, local surgeon who is both practicing and advocating for a new, less invasive option. "This is because they have unicompartmental arthritis and could instead get a better result with less risk and recovery with minimally invasive partial knee resurfacing (MIPKR). Roughly 60-70 percent of the knee replacements I do are partial knees; the rest I do total knee replacements."

The procedure itself consists of an outpatient surgery that utilizes a small high speed burr that requires the surgeon to freehand sculpt only the diseased portion of the knee so that small metal and plastic implants, the same material as used in total knee replacement, are implanted to patch the worn surfaces.

"The majority of arthritic knees are only worn down on one of the two weight bearing surfaces, so in this procedure only the diseased portion is resurfaced, leaving the other healthy parts of the knee natural. Everyone has a different anatomy, total knees are done with cookie cutter cutting guides and big incisions," Dr. Redish explained. "Every total knee is put into the same shape and alignment regardless of the patient's pre-existing anatomy. This technique simply adds a few millimeters of plastic and metal to make up for the cartilage that has been lost, re-establishing each patient anatomy and alignment as it was before the knee became arthritic. It also leaves intact the ACL which is removed in Total Knees, and doesn't cut through the quadriceps muscle."

Dr. Redish learned this technique in 1999, when it was introduced to orthopedic surgeons throughout the world as a long awaited improvement to total knees. It was developed by Dr. John Repicci, a dentist before becoming an orthopedic surgeon.

"It was hard to get into a workshop to learn this back then, so many surgeons wanted to learn it that Dr. Repicci traveled the country to packed audiences of surgeons to learn the technique," Dr. Redish said. "I never would have thought that I would be one of only a handful of surgeons that practice it successfully 20 years later."

Surgeons found the operation difficult to do and reproduce consistently, and four years later the manufacturer stopped promoting the product in favor of a more expensive partial knee that was more invasive but easier for the surgeon to do.

Dr Redish instead helped perfect this operation, and he has done almost 3,000 of them over the last 19 years with a roughly 95% rate of success.

"The study we published of follow up 10-13 years after surgery showed a 94.6 retention of the implant, which is better than most all partial knees, and the results significantly better than total knees as far as patient satisfaction," he said. "I wanted to show that this works, and it holds up over time."

Dr. Redish has presented his work several times in Europe, where partial knees are more commonly done. In the US, only 3.2 % of knee replacements are partial knees.

"I feel very strongly that this operation should be the standard of care for patients with one-sided knee arthritis," he shared. "I am determined to make every effort to reintroduce this method with improved instrumentation to make it easily done by orthopedic surgeons. I am currently working with an implant manufacturer to make this happen."

The procedure takes about 45 minutes and usually patients go home the same day. Most patients need narcotic pain meds only during the first week after surgery. Most also do not need formal physical therapy, they are shown exercises to do on their own. Patients often return to desk jobs after a week, and more physical jobs in a few weeks. There is minimal blood loss and a rate of infection 15 times less than total knee replacement.

If you're wondering about who qualifies as a good candidate for the procedure, Dr. Redish says that anyone with primarily degeneration that is either in the medial or lateral compartment of the knee may be a candidate for MIPKR.

"In some groups of patients it is clearly a better choice than total knee replacement," Dr. Redish added. "For example, younger patients (meaning under 60), whatever they have implanted has a good chance of having to be re-operated on in their lifetime. It makes sense to leave as much bone and ligament natural, so that any subsequent surgeries will be made easier."

In patients over 75 they don't want to spend months getting over a hazardous operation with a long recovery and a partial knee can be done safely for people in their nineties.

He also said that active or athletic patients can greatly benefit.

"These patients will do better by retaining their ACL and leaving things natural," he explained. "By having a stable and natural feeling knee it is easier to be able to walk on uneven surfaces, like doing yard work, hiking through the woods, trout fishing in streams."

To learn more about MIPKR, its benefits, and whether the procedure is right for you, contact Dr. Redish's office at 423-493-5220 or visit his website at